draft-ietf-payload-tsvcis-03.txt   draft-ietf-payload-tsvcis-04.txt 
Payload Working Group Victor Demjanenko Payload Working Group Victor Demjanenko
Internet-Draft John Punaro Internet-Draft John Punaro
Intended Status: Standards Track David Satterlee Intended Status: Standards Track David Satterlee
VOCAL Technologies, Ltd. VOCAL Technologies, Ltd.
Expires: March 30, 2020 September 27, 2019 Expires: April 27, 2020 October 25, 2019
RTP Payload Format for TSVCIS Codec RTP Payload Format for TSVCIS Codec
draft-ietf-payload-tsvcis-03 draft-ietf-payload-tsvcis-04
Status of This Memo Status of This Memo
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
skipping to change at page 3, line 16 skipping to change at page 3, line 16
1.1. Conventions 1.1. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Best current practices for writing an RTP payload format Best current practices for writing an RTP payload format
specification were followed [RFC2736]. specification were followed [RFC2736] [RFC8088].
2. Background 2. Background
The MELP speech coder was developed by the US military as an upgrade The MELP speech coder was developed by the US military as an upgrade
from the LPC-based CELP standard vocoder for low-bitrate from the LPC-based CELP standard vocoder for low-bitrate
communications [MELP]. ("LPC" stands for "Linear-Predictive Coding", communications [MELP]. ("LPC" stands for "Linear-Predictive Coding",
and "CELP" stands for "Code-Excited Linear Prediction".) MELP was and "CELP" stands for "Code-Excited Linear Prediction".) MELP was
further enhanced and subsequently adopted by NATO as MELPe for use by further enhanced and subsequently adopted by NATO as MELPe for use by
its members and Partnership for Peace countries for military and its members and Partnership for Peace countries for military and
other governmental communications as international NATO Standard other governmental communications as international NATO Standard
skipping to change at page 3, line 44 skipping to change at page 3, line 44
voice modes defined in TSVCIS are based on specific fixed rates of voice modes defined in TSVCIS are based on specific fixed rates of
Naval Research Lab's (NRL's) Variable Date Rate (VDR) Vocoder which Naval Research Lab's (NRL's) Variable Date Rate (VDR) Vocoder which
uses the MELPe standard as its base [NRLVDR]. A complete TSVCIS uses the MELPe standard as its base [NRLVDR]. A complete TSVCIS
speech frame consists of MELPe speech parameters and corresponding speech frame consists of MELPe speech parameters and corresponding
TSVCIS augmented speech data. TSVCIS augmented speech data.
In addition to the augmented speech data, the TSVCIS specification In addition to the augmented speech data, the TSVCIS specification
identifies which speech coder and framing bits are to be encrypted, identifies which speech coder and framing bits are to be encrypted,
and how they are protected by forward error correction (FEC) and how they are protected by forward error correction (FEC)
techniques (using block codes). At the RTP transport layer, only the techniques (using block codes). At the RTP transport layer, only the
speech coder related bits need to be considered and are conveyed in speech-coder-related bits need to be considered and are conveyed in
unencrypted form. In most IP-based network deployments, standard unencrypted form. In most IP-based network deployments, standard
link encryption methods (SRTP, VPNs, FIPS 140 link encryptors or Type link encryption methods (SRTP, VPNs, FIPS 140 link encryptors or Type
1 Ethernet encryptors) would be used to secure the RTP speech 1 Ethernet encryptors) would be used to secure the RTP speech
contents. Further, it is desirable to support the highest voice contents.
quality between endpoints which is only possible without the overhead
of FEC.
TSVCIS augmented speech data is derived from the signal processing TSVCIS augmented speech data is derived from the signal processing
and data already performed by the MELPe speech coder. For the and data already performed by the MELPe speech coder. For the
purposes of this specification, only the general parameter nature of purposes of this specification, only the general parameter nature of
TSVCIS will be characterized. Depending on the bandwidth available TSVCIS will be characterized. Depending on the bandwidth available
(and FEC requirements), a varying number of TSVCIS specific speech (and FEC requirements), a varying number of TSVCIS-specific speech
coder parameters need to be transported. These are first byte-packed coder parameters need to be transported. These are first byte-packed
and then conveyed from encoder to decoder. and then conveyed from encoder to decoder.
Byte packing of TSVCIS speech data into packed parameters is Byte packing of TSVCIS speech data into packed parameters is
processed as per the following example: processed as per the following example:
Three-bit field: bits A, B, and C (A is MSB, C is LSB) Three-bit field: bits A, B, and C (A is MSB, C is LSB)
Five-bit field: bits D, E, F, G, and H (D is MSB, H is LSB) Five-bit field: bits D, E, F, G, and H (D is MSB, H is LSB)
MSB LSB MSB LSB
skipping to change at page 5, line 17 skipping to change at page 5, line 15
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Packet Format Diagram Figure 1: Packet Format Diagram
The RTP header of the packetized encoded TSVCIS speech has the The RTP header of the packetized encoded TSVCIS speech has the
expected values as described in [RFC3550]. The usage of the M bit expected values as described in [RFC3550]. The usage of the M bit
SHOULD be as specified in the applicable RTP profile -- for example, SHOULD be as specified in the applicable RTP profile -- for example,
[RFC3551], where [RFC3551] specifies that if the sender does not [RFC3551], where [RFC3551] specifies that if the sender does not
suppress silence (i.e., sends a frame on every frame interval), the suppress silence (i.e., sends a frame on every frame interval), the
M bit will always be zero. When more than one codec data frame is M bit will always be zero. When more than one codec data frame is
present in a single RTP packet, the timestamp is, as always, that of present in a single RTP packet, the timestamp specified is that of
the oldest data frame represented in the RTP packet. the oldest data frame represented in the RTP packet.
The assignment of an RTP payload type for this new packet format is The assignment of an RTP payload type for this new packet format is
outside the scope of this document and will not be specified here. It outside the scope of this document and will not be specified here. It
is expected that the RTP profile for a particular class of is expected that the RTP profile for a particular class of
applications will assign a payload type for this encoding, or if that applications will assign a payload type for this encoding, or if that
is not done, then a payload type in the dynamic range shall be chosen is not done, then a payload type in the dynamic range shall be chosen
by the sender. by the sender.
3.1. MELPe Bitstream Definitions 3.1. MELPe Bitstream Definitions
skipping to change at page 6, line 17 skipping to change at page 6, line 15
The total number of bits used to describe one MELPe frame of 2400 bps The total number of bits used to describe one MELPe frame of 2400 bps
speech is 54, which fits in 7 octets (with two rate code bits). For speech is 54, which fits in 7 octets (with two rate code bits). For
MELPe 1200 bps speech, the total number of bits used is 81, which MELPe 1200 bps speech, the total number of bits used is 81, which
fits in 11 octets (with three rate code bits and four unused bits). fits in 11 octets (with three rate code bits and four unused bits).
For MELPe 600 bps speech, the total number of bits used is 54, which For MELPe 600 bps speech, the total number of bits used is 54, which
fits in 7 octets (with two rate code bits). The comfort noise frame fits in 7 octets (with two rate code bits). The comfort noise frame
consists of 13 bits, which fits in 2 octets (with three rate code consists of 13 bits, which fits in 2 octets (with three rate code
bits). TSVCIS packed parameters will use the last code combination bits). TSVCIS packed parameters will use the last code combination
in a trailing byte as discussed in Section 3.2. in a trailing byte as discussed in Section 3.2.
It should be noted that CODB for both the 2400 and 600 bps modes MAY It should be noted that CODB for MELPe 600 bps mode MAY deviate from
deviate from the values in Table 1 when bit 55 is used as an end-to- the value in Table 1 when bit 55 is used as an end-to-end framing
end framing bit. Frame decoding would remain distinct as CODA being bit. Frame decoding would remain distinct as CODA being zero on its
zero on its own would indicate a 7-byte frame for either rate and the own would indicate a 7-byte frame for either 2400 or 600 bps rate and
use of 600 bps speech coding could be deduced from the RTP timestamp the use of 600 bps speech coding could be deduced from the RTP
(and anticipated by the SDP negotiations). timestamp (and anticipated by the SDP negotiations).
3.1.1. 2400 bps Bitstream Structure 3.1.1. 2400 bps Bitstream Structure
The 2400 bps MELPe RTP payload is constructed as per Figure 2. Note The 2400 bps MELPe RTP payload is constructed as per Figure 2. Note
that CODA MUST be filled with 0 and CODB SHOULD be filled with 0 as that CODA MUST be filled with 0 and CODB SHOULD be filled with 0 as
per Section 3.1. CODB MAY contain an end-to-end framing bit if per Section 3.1. CODB MAY contain an end-to-end framing bit if
required by the endpoints. required by the endpoints.
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
skipping to change at page 8, line 35 skipping to change at page 8, line 33
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| CODA | CODB | CODC | B_13 | B_12 | B_11 | B_10 | B_09 | | CODA | CODB | CODC | B_13 | B_12 | B_11 | B_10 | B_09 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 5: Packed MELPe Comfort Noise Payload Octets Figure 5: Packed MELPe Comfort Noise Payload Octets
3.2. TSVCIS Bitstream Definition 3.2. TSVCIS Bitstream Definition
The TSVCIS augmented speech data as packed parameters MUST be placed The TSVCIS augmented speech data as packed parameters MUST be placed
immediately after a corresponding MELPe 2400 bps payload in the same immediately after a corresponding MELPe 2400 bps payload in the same
RTP packet. The packed parameters are counted in octets (TC). In RTP packet. The packed parameters are counted in octets (TC). The
the preferred placement, shown in Figure 6, a single trailing octet preferred placement SHOULD be used for TSVCIS payloads with TC less
SHALL be appended to include a two-bit rate code, CODA and CODB, than or equal to 77 octets, and is shown in Figure 6. In the
(both bits set to one) and a six-bit modified count (MTC). The preferred placement, a single trailing octet SHALL be appended to
special modified count value of all ones (representing a MTC value of include a two-bit rate code, CODA and CODB, (both bits set to one)
63) SHALL NOT be used for this format as it is used as the indicator and a six-bit modified count (MTC). The special modified count value
for the alternate packing format shown next. In a standard of all ones (representing a MTC value of 63) SHALL NOT be used for
implementation, the TSVCIS speech coder uses a minimum of 15 octets this format as it is used as the indicator for the alternate packing
for parameters in octet packed form. The modified count (MTC) MUST format shown next. In a standard implementation, the TSVCIS speech
be reduced by 15 from the full octet count (TC). Computed MTC = TC- coder uses a minimum of 15 octets for parameters in octet packed
15. This accommodates a maximum of 77 parameter octets (maximum form. The modified count (MTC) MUST be reduced by 15 from the full
value of MTC is 62, 77 is the sum of 62+15). octet count (TC). Computed MTC = TC-15. This accommodates a maximum
of 77 parameter octets (maximum value of MTC is 62, 77 is the sum of
62+15).
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
1 | T008 | T007 | T006 | T005 | T004 | T003 | T002 | T001 | 1 | T008 | T007 | T006 | T005 | T004 | T003 | T002 | T001 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 | 2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
3 | T024 | T023 | T022 | T021 | T020 | T019 | T018 | T017 | 3 | T024 | T023 | T022 | T021 | T020 | T019 | T018 | T017 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
4 | T032 | T031 | T030 | T029 | T028 | T027 | T026 | T025 | 4 | T032 | T031 | T030 | T029 | T028 | T027 | T026 | T025 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
5 | T040 | T039 | T038 | T037 | T036 | T035 | T034 | T033 | 5 | T040 | T039 | T038 | T037 | T036 | T035 | T034 | T033 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
skipping to change at page 10, line 18 skipping to change at page 10, line 20
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
TC+1 | octet count | TC+1 | octet count |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
TC+2 | CODA | CODB | 1 | 1 | 1 | 1 | 1 | 1 | TC+2 | CODA | CODB | 1 | 1 | 1 | 1 | 1 | 1 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 7: Length Unrestricted Packed TSVCIS Payload Octets Figure 7: Length Unrestricted Packed TSVCIS Payload Octets
3.3. Multiple TSVCIS Frames in an RTP Packet 3.3. Multiple TSVCIS Frames in an RTP Packet
A TSVCIS RTP packet consists of zero or more TSVCIS coder frames A TSVCIS RTP packet payload consists of zero or more consecutive
(each consisting of MELPe and TSVCIS coder data) followed by zero or TSVCIS coder frames (each consisting of MELPe 2400 and TSVCIS coder
one MELPe comfort noise frame. The presence of a comfort noise frame data), with the oldest frame first, followed by zero or one MELPe
can be determined by its rate code bits in its last octet. comfort noise frame. The presence of a comfort noise frame can be
determined by its rate code bits in its last octet.
The default packetization interval is one coder frame (22.5, 67.5, or The default packetization interval is one coder frame (22.5, 67.5, or
90 ms) according to the coder bitrate (2400, 1200, or 600 bps). For 90 ms) according to the coder bitrate (2400, 1200, or 600 bps). For
some applications, a longer packetization interval is used to reduce some applications, a longer packetization interval is used to reduce
the packet rate. the packet rate.
A TSVCIS RTP packet without coder and comfort noise frames MAY be A TSVCIS RTP packet without coder and comfort noise frames MAY be
used periodically by an endpoint to indicate connectivity by an used periodically by an endpoint to indicate connectivity by an
otherwise idle receiver. otherwise idle receiver.
TSVCIS coder frames in a single RTP packet MAY be of different coder TSVCIS coder frames in a single RTP packet MAY have varying TSVCIS
bitrates. With the exception for the variable length TSVCIS parameter octet counts. Its packed parameter octet count (length) is
parameter frames, the coder rate bits in the trailing byte identify indicated in the trailing byte(s). All MELPe frames in a single RTP
the contents and length as per Table 1. packet MUST be of the same coder bitrate. For all MELPe coder
frames, the coder rate bits in the trailing byte identify the
contents and length as per Table 1.
It is important to observe that senders have the following additional It is important to observe that senders have the following additional
restrictions: restrictions:
Senders SHOULD NOT include more TSVCIS or MELPe frames in a single Senders SHOULD NOT include more TSVCIS or MELPe frames in a single
RTP packet than will fit in the MTU of the RTP transport protocol. RTP packet than will fit in the MTU of the RTP transport protocol.
Frames MUST NOT be split between RTP packets. Frames MUST NOT be split between RTP packets.
It is RECOMMENDED that the number of frames contained within an RTP It is RECOMMENDED that the number of frames contained within an RTP
skipping to change at page 12, line 23 skipping to change at page 12, line 29
bitrate: specifies the MELPe coder bitrates supported. Possible bitrate: specifies the MELPe coder bitrates supported. Possible
values are a comma-separated list of rates from the following values are a comma-separated list of rates from the following
set: 2400, 1200, 600. The modes are listed in order of set: 2400, 1200, 600. The modes are listed in order of
preference; first is preferred. If "bitrate" is not present, preference; first is preferred. If "bitrate" is not present,
the fixed coder bitrate of 2400 MUST be used. the fixed coder bitrate of 2400 MUST be used.
tcmax: specifies the TSVCIS maximum value for TC supported or tcmax: specifies the TSVCIS maximum value for TC supported or
desired ranging from 1 to 255. If "tcmax" is not present, a desired ranging from 1 to 255. If "tcmax" is not present, a
default value of 35 is used. default value of 35 is used.
[EDITOR NOTE - the value of 35 is suggested based on a
preferred 8kbps TSVCIS coder bitrate.]
Encoding considerations: This media subtype is framed and binary; see Encoding considerations: This media subtype is framed and binary; see
Section 4.8 of RFC 6838 [RFC6838]. Section 4.8 of RFC 6838 [RFC6838].
Security considerations: Please see Section 8 of RFC XXXX. Security considerations: Please see Section 8 of RFC XXXX.
[EDITOR NOTE - please replace XXXX with the RFC number of this [EDITOR NOTE - please replace XXXX with the RFC number of this
document.] document.]
Interoperability considerations: N/A Interoperability considerations: N/A
skipping to change at page 13, line 24 skipping to change at page 13, line 26
Email: victor.demjanenko@vocal.com Email: victor.demjanenko@vocal.com
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: The media subtype depends on RTP framing and Restrictions on usage: The media subtype depends on RTP framing and
hence is only defined for transfer via RTP [RFC3550]. Transport hence is only defined for transfer via RTP [RFC3550]. Transport
within other framing protocols is not defined at this time. within other framing protocols is not defined at this time.
Author: Victor Demjanenko Author: Victor Demjanenko
Change controller: IETF Payload working group delegated from the Change controller: IETF, contact <avt@ietf.org>
IESG.
Provisional registration? (standards tree only): No Provisional registration? (standards tree only): No
4.2. Mapping to SDP 4.2. Mapping to SDP
The mapping of the above-defined payload format media subtype and its The mapping of the above-defined payload format media subtype and its
parameters SHALL be done according to Section 3 of RFC 4855 parameters SHALL be done according to Section 3 of RFC 4855
[RFC4855]. [RFC4855].
The information carried in the media type specification has a The information carried in the media type specification has a
skipping to change at page 14, line 43 skipping to change at page 14, line 43
parameter=value pairs. The string "value" is an integer number in parameter=value pairs. The string "value" is an integer number in
the range of 1 to 255 representing the maximum number of TSVCIS the range of 1 to 255 representing the maximum number of TSVCIS
parameter octets supported. An example of the media representation parameter octets supported. An example of the media representation
in SDP for describing TSVCIS with a maximum of 101 octets supported in SDP for describing TSVCIS with a maximum of 101 octets supported
is as follows: is as follows:
m=audio 49120 RTP/AVP 96 m=audio 49120 RTP/AVP 96
a=rtpmap:96 TSVCIS/8000 a=rtpmap:96 TSVCIS/8000
a=fmtp:96 tcmax=101 a=fmtp:96 tcmax=101
Parameter "ptime" cannot be used for the purpose of specifying the The parameter "ptime" cannot be used for the purpose of specifying
TSVCIS operating mode, due to the fact that for certain values it the TSVCIS operating mode, due to the fact that for certain values it
will be impossible to distinguish which mode is about to be used will be impossible to distinguish which mode is about to be used
(e.g., when ptime=68, it would be impossible to distinguish if the (e.g., when ptime=68, it would be impossible to distinguish if the
packet is carrying one frame of 67.5 ms or three frames of 22.5 ms). packet is carrying one frame of 67.5 ms or three frames of 22.5 ms).
Note that the payload format (encoding) names are commonly shown in Note that the payload format (encoding) names are commonly shown in
upper case. Media subtypes are commonly shown in lower case. These upper case. Media subtypes are commonly shown in lower case. These
names are case insensitive in both places. Similarly, parameter names are case insensitive in both places. Similarly, parameter
names are case insensitive in both the media subtype name and the names are case insensitive in both the media subtype name and the
default mapping to the SDP a=fmtp attribute. default mapping to the SDP a=fmtp attribute.
skipping to change at page 16, line 13 skipping to change at page 16, line 13
tcmax in the answerer response. The answerer alternatively MAY tcmax in the answerer response. The answerer alternatively MAY
identify its own tcmax and rely on TSVCIS ignoring any augmented data identify its own tcmax and rely on TSVCIS ignoring any augmented data
it cannot use. it cannot use.
5. Discontinuous Transmissions 5. Discontinuous Transmissions
A primary application of TSVCIS is for radio communications of voice A primary application of TSVCIS is for radio communications of voice
conversations, and discontinuous transmissions are normal. When conversations, and discontinuous transmissions are normal. When
TSVCIS is used in an IP network, TSVCIS RTP packet transmissions may TSVCIS is used in an IP network, TSVCIS RTP packet transmissions may
cease and resume frequently. RTP synchronization source (SSRC) cease and resume frequently. RTP synchronization source (SSRC)
sequence number gaps indicate lost packets to be filled by PLC, while sequence number gaps indicate lost packets to be filled by Packet
abrupt loss of RTP packets indicates intended discontinuous Loss Concealment (PLC), while abrupt loss of RTP packets indicates
transmissions. intended discontinuous transmissions. Resumption of voice
transmission SHOULD be indicated by the RTP marker bit (M) set to 1.
If a TSVCIS coder so desires, it may send a MELPe comfort noise frame If a TSVCIS coder so desires, it may send a MELPe comfort noise frame
as per Appendix B of [SCIP210] prior to ceasing transmission. A as per Appendix B of [SCIP210] prior to ceasing transmission. A
receiver may optionally use comfort noise during its silence periods. receiver may optionally use comfort noise during its silence periods.
No SDP negotiations are required. No SDP negotiations are required.
6. Packet Loss Concealment 6. Packet Loss Concealment
TSVCIS packet loss concealment (PLC) uses the special properties and TSVCIS packet loss concealment (PLC) uses the special properties and
coding for the pitch/voicing parameter of the MELPe 2400 bps coder. coding for the pitch/voicing parameter of the MELPe 2400 bps coder.
skipping to change at page 17, line 12 skipping to change at page 17, line 13
an RTP payload format's responsibility to discuss or mandate what an RTP payload format's responsibility to discuss or mandate what
solutions are used to meet such basic security goals as solutions are used to meet such basic security goals as
confidentiality, integrity, and source authenticity for RTP in confidentiality, integrity, and source authenticity for RTP in
general. This responsibility lies with anyone using RTP in an general. This responsibility lies with anyone using RTP in an
application. They can find guidance on available security mechanisms application. They can find guidance on available security mechanisms
and important considerations in [RFC7201]. Applications SHOULD use and important considerations in [RFC7201]. Applications SHOULD use
one or more appropriate strong security mechanisms. The rest of this one or more appropriate strong security mechanisms. The rest of this
section discusses the security-impacting properties of the payload section discusses the security-impacting properties of the payload
format itself. format itself.
This RTP payload format and the TSVCIS decoder do not exhibit any This RTP payload format and the TSVCIS decoder, to the best of our
significant non-uniformity in the receiver-side computational knowledge, do not exhibit any significant non-uniformity in the
complexity for packet processing and thus are unlikely to pose a receiver-side computational complexity for packet processing and thus
denial-of-service threat due to the receipt of pathological data. are unlikely to pose a denial-of-service threat due to the receipt of
Additionally, the RTP payload format does not contain any active pathological data. Additionally, the RTP payload format does not
content. contain any active content.
Please see the security considerations discussed in [RFC6562] Please see the security considerations discussed in [RFC6562]
regarding VAD and its effect on bitrates. regarding Voice Activity Detect (VAD) and its effect on bitrates.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
Key Words", BCP 14, RFC 8174, May 2017, 2119 Key Words", BCP 14, RFC 8174, May 2017,
<http://www.rfc-editor.org/info/rfc8174>. <http://www.rfc-editor.org/info/rfc8174>.
[RFC2736] Handley, M. and C. Perkins, "Guidelines for Writers of RTP [RFC2736] Handley, M. and C. Perkins, "Guidelines for Writers of RTP
Payload Format Specifications", BCP 36, RFC 2736, Payload Format Specifications", BCP 36, RFC 2736,
DOI 10.17487/RFC2736, December 1999, DOI 10.17487/RFC2736, December 1999,
<http://www.rfc-editor.org/info/rfc2736>. <http://www.rfc-editor.org/info/rfc2736>.
[RFC8088] Westerlund, M., "How to Write an RTP Payload Format",
RFC 8088, DOI 10.17487/RFC8088, May 2017,
<http://www.rfc-editor.org/info/rfc8088>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<http://www.rfc-editor.org/info/rfc3264>. <http://www.rfc-editor.org/info/rfc3264>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>. July 2003, <http://www.rfc-editor.org/info/rfc3550>.
 End of changes. 20 change blocks. 
54 lines changed or deleted 59 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/